Packaging systems for the control of relative humidity of fresh fruits, vegetables and flowers with simultaneous regulation of carbon dioxide and oxygen

ABSTRACT

A water permeable sealed container for preservation of produce such as fruit, vegetables and flowers made out of three layer laminate corrugated to form, further three to five layer construct. The layers also include a layer of Kraft paper fluting and layer of polymer which is enclosed between two layers of Kraft paper. The container has a lid, which absorbs water vapor and transmits water vapor from the interior of the container to the exterior through micro perforations. The container can also regulate relative humidity within a range of 75% to 85% for some foods by removing moisture from the food generated from respiration and suppressing product decay due to microorganisms. The laminate may be die cut to be formed into a range of box designs for vertical profiles that provide ventilation spaces between containers in a vertical stack and to provide airflow channels within a stack.

FIELD OF THE INVENTION

This invention relates to a novel process and storage container for themodified atmosphere preservation of fresh fruits, vegetables and/orflowers using preferential relative humidity levels. More particularlythe invention pertains to the preserving of the food integrity and foodsafety in a sealed container which permits the exchange of oxygen carbondioxide and water vapour to maintain high levels of carbon dioxide, lowlevels of oxygen and intermediate levels of relative humidity foroptimum preservation of foods at refrigerated temperatures for extendedstorage periods.

BACKGROUND OF THE INVENTION

Consumers have come to expect the availability of a wide range forfresh, ripe fruits, vegetables and flowers year round. While most if notall of these commodities are available year round from either thesouthern or northern hemispheres, they are often not available due tothe high cost of air-freight or the produce is picked immature toprovide the necessary storage life required for transport anddistribution but does not achieve the full ripeness of a premiumproduct. Fruit picked immature will not have the sugar content nor theability to develop full flavor or ripeness even if exposed to a ripeningprocess. In addition, fruit and vegetables picked immature are oftenmore susceptible to mold, yeast and bacterial diseases that fullyripened fruit and vegetables.

Most modified atmosphere packaging systems use sealed boxes or bags withor without perforations to create high levels of carbon dioxide (5% to20% CO₂) plus low levels of oxygen (1% to 15% O₂) to suppress productrespiration to conserve the products metabolites and maintain quality.Most of these applications provide an elevated relative humidity aroundthe product to prevent desiccation. While this application has a shortterm benefit, respiration of the product generates moisture whichdevelops a saturated environment leading to the growth of bacteria,yeast and molds which affect product quality and food safety. Inaddition, excessively high moisture levels lead to softening andnecrosis of the product resulting in the rapid deterioration of quality.

Many fresh fruits, vegetables and flowers maintain their respectivequality in storage environments that have relative humidity maintainedbetween 84% RH and 94% RH at low temperatures. However, for thoseproducts highly susceptible to mold, yeast and/or bacterial growth (i.e.fresh-cut flowers (roses), bell peppers, mushrooms, berries etc.) arelative humidity of 75% to 80% is preferred as the lower relativehumidity will suppress microbial growth and provide for optimum qualityretention.

Modification of the gas composition in the atmosphere within a packagearound the food can prolong the storage life of the fruit, vegetable andflowers. Modified Atmosphere Packaging (MAP) is an application whichuses the respiring food to reduce the oxygen level and accumulate thecarbon dioxide levels within a package. The lower oxygen and highercarbon dioxide atmosphere slows the respiration rate and quality loss ofthe food and suppresses microbial vegetative growth and sporegermination leading to product quality loss (Powrie and Skura, “ModifiedAtmosphere Packaging of Fruits and Vegetables”, Ellis Horwood, 1991,pages 169-245; “Modified Atmosphere Packaging”, A. Brody, K. Marsh Eds.The Wiley Encyclopaedia of Packaging 1023 pages, Modified AtmosphereApplications to Food, Agriculture and Agri-Food Canada, 1986, 86 pages).

The use of laminated papers are commonly used for the corrugation ofboxes for storage of produce and food that generate high humidityinternally or are stored in high relative humidity atmospheres for anextended period of time. These laminates are used to replace paraffinwaxed boxes which are non-recyclable. While these laminates areconstructed of two layers of kraft paper with an internal layer of low,medium, or high density polyethylene or other plastic material, thelaminates do not have a function other than maintaining the strength ofthe formed box in water saturated environments.

A refinement of the three layer laminate was developed by Wu et al.(U.S. Pat. No. 5,575,418, issued 19 Nov. 1996) and U.S. Pat. No.5,609,293 (issued 11 Mar. 1997) and Clough et al U.S. Pat. No. 6,050,412(issued 18 Apr., 2000) which developed a series of three layer laminatesusing a range of plastic materials and featured 150 to 200 g Kraftlaminated with polymeric film and a third layer consisting of a thinlayer of machine finish or machine glaze fine paper. The plastic filmcharacteristics and thicknesses were selected to provide the three layerlaminates with selected permeabilities in the range of 6000 to 30,000ccO₂/m²-24 hr at 1 atm and 5000 to 28,000 ccCO₂/m²-24 hr at 1 atm and20° C. These laminates when corrugated and formed into a range of boxdesigns were able to create modified atmospheres in the box within therange of 5% to 20% oxygen and 1% to 10% carbon dioxide using the productrespirations and selected exchange of oxygen and carbon dioxide with theambient atmosphere. While the adaptation of the permeable liner was aleto create modified atmospheres for oxygen and carbon dioxide, therelative humidity was between 94% and 100% RH due to equilibriummoisture exchange with the produce and the water vapor given off fromthe produce through respiration. The laminates created in theseinventions did not have water vapor exchange capabilities, and theresultant high relative humidity created within the box resulted incondensation and accelerated microbial growth due to yeasts, molds andfungi and product quality loss due to condensation on the produce.

A variation of the invention was introduced by Machado et at (US PatentPublication No. US2004/0188507) which featured a transparent impermeablepolyethylene top which was sealed to an open faced tray. This adaptationprovided for visibility of the product and improved the heat removal andproduct temperature maintenance of the product during transport. Whilethe lid was treated with an anti-fog to prevent condensation on the lid,the lid and the laminate used in the construction of the tray wereimpervious to water vapor transmission.

In a separate application Nir et. al (U.S. Pat. No. 6,190,710) used aseries of nylon materials to create sealed bags for the creation ofmodified atmospheres for fruit and vegetables. Although the nylonmaterials could absorb moisture from the interior of the bag, the filmswere barriers to the transmission of oxygen and carbon dioxide throughthe films. To allow oxygen to penetrate into the bag to preventanaerobiosis and to prevent carbon dioxide created from respiration fromexceeding 20% CO₂, a series of microperforations were created in thefilm to allow gas transmission. The modified atmospheres created by thismethod were limited to combinations where the oxygen and carbon dioxidecontents totalled 20%.

A novel functional modified atmosphere package which can provide a rangeof beneficial relative humidity levels is described. The design and useof moisture absorbing materials can be used to create high carbondioxide levels within the package through the package design and/ormicro-perforations. The package or box can be used in a variety ofshapes and configurations for commercial and institutional use and canimpart significant benefits in maintaining food quality, extending theusable life of produce and provide greater consumer confidence in foodsafety.

The related art cited previously and the limitations referenced aremeant to be illustrative and not exclusive. Additional limitations ofthe related art will become apparent to those of skill in the art uponthe description of the specifications and study of the designs noted inthe figures.

SUMMARY OF THE INVENTION

The following embodiments and aspects thereof are described andillustrated in conjunction with systems, tools, and methods which aremeant to be illustrative and not limiting in scope. In variousiterations and embodiments, one or more of the previously describedtechnical shortfalls or problems have been compensated for oreliminated, while other embodiments are directed to other improvements.

The invention describes a closed gas impermeable paperboard packagecomprising several iterations which may include a one-piece box design,a three piece Bliss box design or a box and a lid where the box and lidmay consist of a three layer laminate or the lid may be a clear oropaque polymeric lid with gas permeable properties and/or water vapourtransmission properties.

This invention relates to a novel application which provides forsimultaneous control and regulation of water vapour transmission throughan engineered three layer laminate and oxygen and carbon dioxidetransmission through a novel sealing process and/or micro-perforationsto maintain the retention of quality of fresh fruit, vegetables andflowers held at refrigerated temperatures for extended storage periodsof 10 to 50 days.

This invention consists of several novel components for both thecontainer body and the lid. The container body consists of a laminatecomprised of:

-   -   1/ A primary structural layer of bleached or unbleached Kraft        paper consisting of 150 to 250 g/m² virgin or recycled fibres;    -   2/ An intermediate layer of polymeric coating with water vapour        transmission properties with or without oxygen and carbon        dioxide transmission properties;    -   3/ A third layer comprising a smooth thin layer of machine        finish or machine glaze consisting of 20 to 100 g/m² of natural        or bleached virgin or recycled Kraft paper.

The three layer laminate can be used to create a three or more layercorrugate using standard corrugation practices. The laminate can be usedto create a wide range of box types and configurations.

The objectives of this invention, which are to be achieved from thedesign, composition and implementation of this system, are:

-   -   1/ retention of quality of whole or fresh-cut fruit, vegetables        and flowers;    -   2/ retention of moisture or a slight reduction of moisture (+ or        −2% of total weight of the product    -   3/ inhibition of mold, yeast and bacterial development on fruit,        vegetables and flowers;    -   4/ inhibition of off-flavors that develop from yeast, mould or        bacteria growth and/or physiological senescent physiological        processes;    -   5/ inhibition of chlorosis and necrosis as a result of loss of        energy reserves (i.e. sugars, ATP, ADP and AMP).

The invention consists of constructing a novel three layer laminateinclusive of the following:

-   -   1/ utilizing a supportive layer of Kraft for rigidity and        strength which may consist of 150 g to 250 g/m²/virgin or        recycled paper;    -   2/ lamination of a layer of polyamide (nylon 6, 11, 12 and        similar water absorbing plastic material or combinations        thereof) nylon placing the product in a custom designed        container consisting of an open-box structure with a custom        designed profile that provides for air movement above and below        the container.

The three layer laminate once constructed should provide a barrier tooxygen and carbon dioxide transmission with oxygen transmission ratesof: 0 to 200 cm³ per m² per 24 hours at 25° C. at 1 atm, and carbondioxide transmission rates of: 0 to 800 cm³ per m² per 24 hours at 25°C. at 1 atm.

The invention requires the three layer laminate to be corrugated to aflute and a third layer of Kraft paper. The laminate may be positionedon the interior or exterior of the container or alternatively thelaminate may comprise both layers on either side of the flute in thefinal corrugate construction.

The inventions describes the formation of the corrugated laminate into arange of differing container shapes and constructs which are compatiblewith an airtight sealed lid. The laminate in the formed container shouldbe free of pinholes resulting from creasing, folding and/or sealing thecontainer.

The described lid can consist of a single piece that may include:

-   -   1/ a rigidized sheet of plastic material thermoformed and        constituted from a range of plastic materials including but not        limited to polyamide (nylon 6, 11, 12 or 66 and blends thereof),        polycarbonate, polyethylene, polyethyleneterepthalate,        polypropylene, polystyrene, polyvinylchloride, and mixtures        thereof;    -   2/ a design that provides for a friction fitting lid that is        self levelling and which can seal to the laminate of the located        at the top profile of the corrugated container;    -   3/ a design that provides for an air tight seal with the bottom        of the container which contains the airtight laminate.

The water vapor absorption and permeability can be determined byregulating the composition of the polymer in the laminate, or byregulating the thickness of the extrusion of the polymer in forming thelaminate.

The oxygen and carbon dioxide gas barrier properties can be modified andcustomized by regulating the composition of the polymer in the laminateor by regulating the thickness of the extrusion in the laminate. Howeverthis invention describes gas barrier applications for oxygen and carbondioxide gas and does not extend to gas permeabilities above 200 cm³ perm² per 24 hours at 25° C. at 1 atm for oxygen, and above 800 cm³ per m²per 24 hours at 25° C. at 1 atm for carbon dioxide.

The prescribed lid may be transparent or may be colored in its formationto provide colored coding for operational efficiencies while retainingtransparency. The lid may also be opaque.

The lid may be sealed to the container by adhesives consisting of butlimited to silicone, liquid or paste polymeric sealants, hot melt gluesand/or gas impermeable or permeable adhesive tapes.

The sealed container may provide for oxygen diffusion into the constructbe a series of regulated openings which may consist of:

-   -   1/ Microperforations of 50 to 90 micron diameter. The number of        microperforations will be determined by the surface area:produce        volume, the produce respiration rate and the temperature.        However in most cases the number of microperforations will range        from 1 to 100 per container;    -   2/ Mircoperforations may be placed in the lid, the body of the        container or both locations;    -   3/ Mircoperforations may occur at the container body to lid seal        depending upon the sealant used;    -   4/ Microperforations may be created at the folds in the        formation of the corrugated container;    -   5/ Mircoperforations should be uniformly distributed across the        container and/or lid.

The container top and bottom materials can to maintain internal humidityin the range of 75% RH to 90% RH by the use of polyamide materials andthickness of construction.

Prior to sealing the package, air may be removed from the package byvacuum.

The sealed package of respiring fresh food can contain a ratio mass(grams) to total package volume (cm³) of between 0.3 to 0.6. Theheadspace gas composition of the sealed package can be between 1 and 50%carbon dioxide and 0.5% to 15% oxygen with internal relative humidity of75% RH to 100% RH.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed containers are described diagrammatically in the followingdrawings wherein:

FIG. 1 provides a plan view of the basic embodiments of the blankconstruct that, once folded, forms the corrugated container.

FIG. 2 provides an alternate plan view of the basic embodiments of theblank construct that, once folded, forms the corrugated container.

FIG. 3 provides top, side and perspective views of the basic embodimentsof the lid construct.

FIG. 4 provides an alternate top, side and perspective views of thebasic embodiments of the lid construct.

The drawings are not necessarily to scale and the embodiments aresometimes illustrated by graphic symbols, phantom lines, diagrammaticrepresentations and fragmentary views. In certain instances, detailswhich are not necessary for an understanding of the disclosed containersor which may render other details difficult to perceive may have beenomitted. It should be understood, of course, that the disclosure is notnecessarily limited to the particular embodiments illustrated herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout the following description, specific details are set forth inorder to provide a more thorough understanding of the invention.However, the invention may be practised without these particulars. Inother instances, well know elements have not been shown or described indetail to avoid unnecessarily obscuring the invention. Accordingly, thespecification is to be regarded in an illustrative, rather than arestrictive, sense.

This invention provides a novel packaging application involving thepreparation of washed, sanitized, fruits and vegetables followed byhumidity regulated, modified atmosphere packaging of the product fortransport, storage and/or distribution to retail, wholesale and/orinstitutional markets. The fresh product continues to respire in thesealed container and consumes oxygen and releases carbon dioxide intothe chamber environment and is subject to beneficially high carbondioxide and reduced oxygen concentrations. This state provides forreduction of product respiration, inhibition of microbiological growthand spore germination and inhibition of senescence promoting ethyleneaction thereby maintaining product ripeness and retarding deteriorationof the product.

The functional, recyclable humidity regulating/modified atmospherestorage container and lid is illustrated in FIGS. 1, 2, 3 and 4. Theapparatus provides for the simultaneous and/or independent regulation ofwater vapor, carbon dioxide and oxygen, transmission between theinterior and exterior of the sealed package and the ambient storageatmosphere. Water vapor transmission is regulated by the absorption ofwater vapor by the polyamide layer contained in the three layerlaminate. Oxygen and carbon dioxide transmission is regulated by the useof micro-perforations in the lid and/or the container and/or the lid tocontainer seal. Generally if micro-perforations are used the totalsurface area would be in the range of 50 to 200 microns and can becustomized for specific product categories. The lid is perforated withmicro-perforations with total perforation surface area up to 1% of thetotal sealed package surface area.

According to the invention, optimum maturity fruits, vegetables andflowers are placed into the container and sealed in the containerconstructed with the appropriate linerboard for maintenance of thedesired internal relative humidity and the sealed container and lid withthe appropriate microperforation surface area for the attainment of highcarbon dioxide levels (5% to 20%) and low oxygen levels (15% to 1%) inthe headspace of the container after 7 days of storage at 1 C.Sufficient microperforations are provided for specific products andvolumes to ensure that oxygen levels do not fall below 1% whereanaerobic respiration can affect product quality and food safety maybecome an issue. Specifically, the film oxygen transmission ranges forratio mass (grams) to total package volume (cm³) of between 0.3 to 0.6would be applicable as:

The invention provides for a range of relative humidity, carbon dioxideand oxygen conditions through creation and application of:

-   -   1. A novel three layer laminate which is constructed from 50 to        200 g/m² virgin bleached or unbleached kraft paper laminated        with plastic material consisting of a range of plastic materials        including but not limited to polyamide (nylon 6, 11, 12 or 66        and blends thereof), polycarbonate, polyethylene,        polyethyleneterepthalate, polypropylene, polystyrene,        polyvinylchloride, and mixtures thereof and further laminated at        a rate of 20 to 100 g/m² to a thin tissue consisting of 10 to        100 g/m² bleached or unbleached paper, to form a construct        capable of absorbing and transmitting water vapor and providing        a barrier to oxygen and carbon dioxide transmission;    -   2. Corrugation of the prepared laminate with kraft paper to form        a three to five layer construct and subsequent box formation;    -   3. A unique plastic lid that may be constituted from a range of        plastic materials including but not limited to polyamide (nylon        6, 11, 12 or 66 and blends thereof), polycarbonate,        polyethylene, polyethyleneterepthalate, polypropylene,        polystyrene, polyvinylchloride, and mixtures thereof of a design        that provides an airtight seal to the laminate portion of the        three to five layer corrugate.

The three layer laminate may be constructed from 50 to 200 g/m² virginbleached or unbleached kraft paper laminated with plastic materialconsisting of a range of plastic materials (10 to 100 g/m²) includingbut not limited to polyamide (nylon 6, 11, 12 or 66 and blends thereof),polycarbonate, polyethylene, polyethyleneterepthalate, polypropylene,polystyrene, polyvinylchloride, and mixtures thereof and furtherlaminated to a thin tissue consisting of 20 to 100 g/m² bleached orunbleached paper, to form a construct capable of absorbing andtransmitting water vapor and providing a barrier to oxygen and carbondioxide transmission.

The three layer laminate may be created by

The lid may be constructed from a range of plastic materials includingbut not limited to polyamide (nylon 6, 66, 11, Or 12 and blends thereof)polycarbonate, polyethylene, polyethyleneterepthalate, polypropylene,polystyrene, polyvinylchloride, and mixtures thereof.

The three layer laminate once corrugated into a three or five layerconstruct may be die cut to a wide range of designs that may be furtherformed into a range of box designs (FIGS. 1, 2, 3, and 4) that providefor flexible vertical profile that provide ventilation spaces betweenboxes in a vertical stack and to provide air flow channels within astack, within an individual pallet and among pallets constituting acontainer load.

The container design is may have the functional attributes that providefor interlocking of the boxes within a stack by tabs, adhesion of twoadjoining boxes in a vertical stack by adhesives and/or tape and/or bystrapping and the use of corner posts to secure a pallet load as asingle unit.

The container should have rigid walls with high water vapor transmissionand oxygen and carbon dioxide barrier properties. The container laminateand lid properties should provide permeability ranges for water vapourof 1 to 10 g H₂O per mm-m² per 24 hr at 25° C. at 80-95% RH; oxygentransmission rates of: 10 to 200 cm³ per m² per 24 hours at 25° C. at 1atm; and carbon dioxide transmission rates of: 10 to 800 cm³ per m² per24 hours at 25° C. at 1 atm.

The container and lid microperforations provide for oxygen:carbondioxide diffusion ratio may be in the range of 1.0:1.0 or 1.5.

The microperforations provided in the lid and/or container may beinserted to provide a range of oxygen and carbon dioxide transmissionsfor the lid/container construct for specific product applications:

Category 1:

High Barrier:

-   -   Oxygen transmission rates of: 10 to 1500 cm³ per m² per 24 hours        at 25° C. at 1 atm    -   Carbon dioxide transmission rates of: 10 to 2000 cm³ per m² per        24 hours at 25° C. at 1 atm.    -   Sample product applications: Baby carrots, beets and other root        crops; fresh cut salads.

Category 2:

Medium Barrier:

-   -   Oxygen transmission rates of 1500 to 5000 cm³ per m² per 24        hours at 25° C. at 1 atm    -   Carbon dioxide transmission rates of: 1500 to 7500 cm³ per m²        per 24 hours at 25° C. at 1 atm.    -   Sample product applications: Fruits such as cantaloupe, honey        dew, tomatoes, apple, pears, cherries, grapes, peaches,        nectarines, kiwi, strawberries, tomatoes, cucumbers (in general        citrus, pome and drupe fruits, berries and greenhouse crops).

Category 3:

Low Barrier (High Permeability):

-   -   Oxygen transmission rates of: 25,000+over cm³ per m² per 24        hours at 25° C. at 1 atm    -   Carbon dioxide transmission rates of 25,000+cm³ per m² per 24        hours at 25° C. at 1 atm.    -   Sample product applications: Mushrooms, asparagus.

The novel apparatus provides additional maintenance of food productquality with options to regulate the relative humidity within the sealedpackage through the selection of lid, container and film materials.Fabrication of the film, container and/or lid from a range of polyamidematerials provides the ability to absorb moisture and regulate relativehumidity levels within the sealed package. Maintenance of internalrelative humidity levels at approximately 75% RH to 90% RH maintainsproduct quality by removing residual surface water from the product,providing slight moisture reduction of the product, removal of watervapour generated from product respiration and maintain a relativehumidity level that suppresses microbial vegetative growth and sporegermination (below 80% RH).

Many fresh fruit, vegetable and flowers have demonstrated a 2 times to 4times increase in the effective storage, distribution and shelf life ifthe product is stored without residual moisture after washing and driedto original it original weight or within +/−1% (wt/wt) of its originalweight.

Fresh produce generates water as a product of respiration. This moisturewhen added to an enclosed system increases the relative to humiditybeyond the equilibrium value. In most cases, equilibrium relativehumidity between the produce and surrounding atmosphere in an enclosedenvironment is established at 90% to 94% RH. The present novelapplication provides for the release of incremental moisture resultingfrom natural respiration of the produce, eliminates or reducescondensation in the internal atmosphere of the package and provides forthe maintenance of optimal internal relative humidities of 75% to 90%.

The described invention provides for the maintenance of an optimum rangeof moisture contents with fresh fruit, vegetables and flowers and in thesurrounding enclosed package environment to preserve product quality,freshness and storage, distribution and shelf lie. In addition, a secondlayer of technology is created through the application of modifiedatmospheres generated by using a sealed container system withmicroperforations to create high levels of carbon dioxide (5% to 20%CO₂) plus low levels of oxygen (1% to 15% O₂) to suppress productrespiration to conserve the products metabolites and maintain quality.The present application has long term benefits in suppressing therespiration of the product, maintaining optimal product moisture contentand maintaining a favorable internal relative humidity environment thatsuppresses growth of bacteria, yeast and molds which affect productquality and food safety.

Example 1

The process for preparation and preservation of fresh peaches (cv. RedHaven) using the invention, involves the following:

-   -   1. Fresh peaches were harvested at a full ripe maturity        indicated by a lack of chlorophyll in the ground cover of the        flesh with a firmness of 4 to 6 kg-f fruit firmness;    -   2. The fruit were sanitized with a 100 ppm solution of chlorine,        dried, cooled to 1° C. and packed in the described container        constructed with 30 g per m² nylon 6/12 laminate with oxygen        transmission rate 5000 cm³ per m² per 24 hours at 25° C. at 1        atm as created with 10 microperforations in a container        containing 9 kg of fresh peaches. Oxygen atmospheres were        maintained between 2 and 3% oxygen while carbon dioxide        atmospheres were maintained at 5% to 6%;    -   3. A control sample of peaches of the same maturity was placed        in a similar modified atmosphere package maintained at 94% RH to        100% RH;    -   3. Peaches in the control and those stored in the invention were        held at 1° C. for periods of 10, 20 and 30 days;

Peaches stored in the control packages demonstrated an increase inindividual fruit volume after 10 days of storage. The increased fruitvolume was associated with a decrease in fruit density and a lack ofjuiciness dryness) when evaluated by 5 sensory panelists. The increasein volume was associated with an increase in water uptake resulting fromthe high relative humidity in the package.

Peaches stored in the invention at relative humidity maintained at 80%to 85% RH showed no increase in fruit volume or decrease in fruitdensity after 30 days. Fruit stored in the invention at relativehumidity of 80% to 85% RH remained juicy and acceptable to sensorypanelist for up to 40 days with an average sensory score of 3.5 rated ona full scale of 5 (5 being excellent and 3 deemed to be marginallyacceptable). Browning and wilting of the fruit was not evident after 40days. No off odors or evidence of mould or decay were identified.

Example 2

The process for preparation and preservation of perishable kiwi fruitusing the invention, involves the following:

-   -   1. Ready-to-eat firm mature ripe kiwi fruit (cv. Hayward;        firmness of 3 to 5 kgf) that are free of obvious decay are        selected, washed with or 100 ppm chlorine if available and        dried;    -   2. Kiwi fruit are packed in preformed trays composed either of        wood fibre or plastic (wood fiber is preferred) and placed in        the container;    -   3. The kiwi fruit are cooled to 0° C. and the container is        sealed by placing the plastic top in place with the desired        sealant;    -   4. The kiwi fruit were sealed in the package with        microperforations sufficient to provide an oxygen transmission        rate of 3000 cm³ per m² per 24 hours at 25° C. at 1 atm and        stored at 0° C. for up to 28 days.

The quality of the kiwi fruit compared to conventionally packed controls(corrugated boxes) controls demonstrated superior eating quality andfreedom from decay after 28 days in the container. Whereas control fruitwere noticeably shrivelled, soft and showed an 18% incidence of decay,the fruit packed in the novel box technology showed typical kiwi fruitflavor and sensory characteristics. Incidence of decay of kiwi fruitstored in the novel container was not evident. Kiwi fruit placed in theconventional corrugated containers were rated as unacceptable forconsumption after day 8 of storage by a 5 member trained sensory panel.

Kiwifruit stored in the described novel container were rated by thesensory panel as excellent on day 20 of storage and as acceptable at day28. Fruit pieces were bright green and opaque with texture equivalent tothe texture at day 0. Characteristic kiwi flavour was maintainedthroughout the 28 days storage period without noticeable off-flavors(ethanol and acetaldehyde), shrivelling of the skin or decay as found inthe control fruit.

Example 3

The process for preparation and preservation of fresh mushrooms usingthe invention, involves the following:

-   -   1. Fresh white mushrooms were harvested closed cap maturity;    -   2. The fruit were washed in a fresh water cascade and dried by        warm dry air to the original weigh, cooled to 1° C. and packed        in the described container constructed with 35 g per m² nylon        6/66 laminate with oxygen transmission rate of 30,000 cm³ per m²        per 24 hours at 25° C. at 1 atm created with 90        microperforations in a container containing 5 kg of fresh        mushrooms. Oxygen atmospheres were maintained between 3 and 5%        oxygen while carbon dioxide atmospheres were maintained at 7% to        10%;    -   3. A control sample of mushrooms of the same maturity was placed        in a similar modified atmosphere package maintained at 94% RH to        100% RH;    -   4. Mushrooms in the control and those stored in the invention        were held at 1° C. for periods of 5, 10 and 15 days;

Mushrooms stored in the control packages appeared slimy after ten daysat high relative humidity storage. Analysis of the microbial contentindicated pseudomonas content of more than 1,000,000 colony formingunits (CFU), product was not considered fit for evaluation orconsumptions by a trained panel.

Mushrooms stored in the invention at relative humidity maintained at 75%to 80% RH were evaluated by a 5 member panel as acceptable as acceptablefor up to 15 days with an average sensory score of 3.25 rated on a fullscale of 5 (5 being excellent and 3 deemed to be marginally acceptable).Browning and wilting of the fruit was not evident after 15 days. No offodors or evidence of mold or decay were identified.

Example 4

The process for preparation and preservation of fresh grapes (cv.Thompson Seedless, Perlette) on the stem using the invention, involvesthe following:

-   -   1. Fresh grapes were harvested at a full ripe maturity indicated        by sugar/acid ratio (soluble solids content);    -   2. The fruit were sanitized with a 100 ppm solution of chlorine,        dried, cooled to 1° C. and packed in the described container        constructed with 35 g per m² nylon 6/12 laminate with oxygen        transmission rate 4000 cm³ per m² per 24 hours at 25° C. at 1        atm as created with 15 microperforations in a container        containing 9 kg of fresh grapes. Oxygen atmospheres were        maintained between 2 and 3% oxygen while carbon dioxide        atmospheres were maintained at 5% to 6%;    -   3. A control sample of grapes of the same maturity was placed in        a similar modified atmosphere package maintained at 94% RH to        100% RH;    -   4. Grapes in the control and those stored in the invention were        held at 1° C. for periods of 10, 20 and 30 days;

Grapes stored in the control packages at elevated relative humidity of94% RH to 100% RH demonstrated an increase in individual fruit weightafter 5 days of storage and continued to increase with extended storagetime. The increased fruit weight was associated with an increase in theproportion of the number of fruit detached from the vine. The increasein individual fruit absorption of water vapor increased the turgidity ofthe fruit and resulted in the fruit separation from the vine.

Grapes on the vine stored in the invention at relative humiditymaintained at 75% to 85% RH showed no increase in individual fruitweight fruit density after 30 days of storage. Individual fruit weightremained +/− within 1% of the initial weight. Fruit stored in theinvention at relative humidity of 75% to 85% RH remained juicy andacceptable to sensory panelist for up to 35 days with an average sensoryscore of 3.8 rated on a full scale of 5 (5 being excellent and 3 deemedto be marginally acceptable). Browning and wilting of the fruit was notevident after 40 days. No off odors or evidence of mould or decay wereidentified.

Example 5

The process for preparation and preservation of fresh bell peppers usingthe invention, involves the following:

-   -   1. Fresh greenhouse grown bell peppers were harvested at a full        ripe maturity indicated by color, heat units and productions        days;    -   2. The fruit were sanitized with a 200 ppm solution of chlorine,        dried, cooled to 1° C. and packed in the described container        constructed with 35 g per m² nylon 6/12 laminate with oxygen        transmission rate 4000 cm³ per m² per 24 hours at 25° C. at 1        atm as created with 15 microperforations in a container        containing 7 kg of fresh peppers. Oxygen atmospheres were        maintained between 2 and 3% oxygen while carbon dioxide        atmospheres were maintained at 5% to 6%;    -   3. A control sample of peppers of the same maturity was placed        in a similar modified atmosphere package maintained at 94% RH to        100% RH;    -   4. Bell peppers in the control and those stored in the invention        were held at 1° C. for periods of 10, 20 and 30 days;

Bell peppers stored in the control packages at elevated relativehumidity of 94% RH to 100% RH demonstrated an increase in individualfruit weight after 7 days of storage and continued to increase withextended storage time. The increased fruit weight was associated with anincrease in the incidence of mold in the stem cavity of the fruit.

Bell peppers stored in the invention at relative humidity maintained at75% to 85% RH showed no increase in individual fruit weight after 25days of storage. Individual fruit weight remained +/− within 1.5% of theinitial weight. Fruit stored in the invention at relative humidity of75% to 85% RH remained free of overt mold symptoms and acceptable tosensory panelists for up to 35 days with an average sensory score of 4.0rated on a full 5 point scale.

As will be apparent to those skilled in the art with respect to theforgoing disclosures, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined in the followingclaims.

Most modified atmosphere packaging systems use sealed boxes or bags withor without perforations to create high levels of carbon dioxide (5% to20% CO₂) plus low levels of oxygen (1% to 15% O₂) to suppress productrespiration to conserve the products metabolites and maintain quality.Most of these applications provide an elevated relative humidity aroundthe product to prevent desiccation. In addition the water vapourproduced from the respiration of the produce contributes to excessivelyhigh level of relative humidity that exceeds the equilibrium humidityestablished under passive conditions. While the passive application hasa short term benefit, respiration of the product generates moisturewhich develops a saturated environment leading to the growth ofbacteria, yeast and molds which affect product quality and food safety.In addition, excessively high moisture levels lead to softening andnecrosis of the product resulting in the rapid deterioration of quality.

As will be apparent to those skilled in the art with respect to theforgoing disclosures, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined in the followingclaims.

1. A water permeable sealed container for the preservation of freshfruits, vegetables and flowers that consists of: a) A three layer waterpermeable laminate corrugated to form a further three to five layerconstruct consisting of one or two layers of kraft paper fluting and afurther one or two layers of kraft paper; and b) A water permeable lidthat is sealed by a range of adhesives and/or tape to the laminate.
 2. Asealed container system and lid (FIG. 1, FIG. 2, FIG. 3 and FIG. 4) thatbe designed in various shapes, sizes and container designs.
 3. A sealedcontainer system and lid for the preservation of fresh fruits,vegetables and/or flowers modified atmosphere package between 1% and 15%oxygen and 1% and 20%% carbon dioxide at relative humidity between 75%RH and 100% RH.
 4. A sealed container that includes a three layerlaminate that consists of: a) A first layer of 150 to 250 g per m² kraftpaper; b) A layer 10 to 100 g per m² of water permeable polymer that maybe constituted from a range of plastic materials including but notlimited to polyamide (nylon 6, 11, 12 or 66 and blends thereof),polycarbonate, polyethylene, polyethyleneterepthalate, polypropylene,polystyrene, polyvinylchloride, and mixtures thereof; c) A second layerof 20 to 100 g per m² kraft paper which effectively encloses thepolymeric film between the two layers of kraft paper.
 5. A sealedcontainer that is constituted from a three to five layer corrugateformed by the corrugation and adhesion of the laminate to a kraft paperflute and a further layer of kraft paper.
 6. A sealed container that isformed by die cutting the corrugate sheet into a range of containershapes that may include constructs shown in FIG. 1 and FIG.
 2. 7. Asealed container that is formed from kraft paper that is either bleachedor unbleached.
 8. A sealed container that is formed from kraft paperthat consists of either virgin or recycled wood fiber.
 9. A sealedcontainer that consists of a thermoformed polymeric lid that may beconstituted from a range of plastic materials including but not limitedto polyamide (nylon 6, 66, 11, Or 12 and blends thereof) polycarbonate,polyethylene, polyethyleneterepthalate, polypropylene, polystyrene,polyvinylchloride, and mixtures thereof.
 10. A sealed container thatdeploys several methods to provide an airtight seal between the laminateand the lid including but not limited to: a) A lid with friction fitcompressed physical attachment to the laminate; b) A lid with adhesiveapplied to the lid edges at the point of contact with the laminate ofthe container; c) A lid design that is sealed to the laminate of thecontainer with gas barrier adhesive tape.
 11. A sealed container thatuses a laminate and lid that absorbs water vapour and transmits watervapour from the interior of the container (80% to 100% RH) to theexterior of the container (10% RH to 50% RH).
 12. A sealed containerthat contains a laminate and lid that have low permeabilities to thetransfer of oxygen and carbon dioxide gas.
 13. A sealed container thatuses a range of microperforations (60 to 90 microns in diameter) ineither the container laminate and/or the lid
 14. A sealed container thatprovides a range of microperforations designed for specific packagevolumes, product type and respiration to provide for the followingconditions: Category 1: High Barrier Film: Oxygen transmission rates of:100 to 1500 cm³ per m² per 24 hours at 25° C. at 1 atm Carbon dioxidetransmission rates of: 100 to 2000 cm³ per m² per 24 hours at 25° C. at1 atm. Sample product applications: Baby carrots, beets and other rootcrops; fresh cut salads. Category 2: Medium Barrier Film: Oxygentransmission rates of: 1500 to 5000 cm³ per m² per 24 hours at 25° C. at1 atm Carbon dioxide transmission rates of: 1500 to 7500 cm³ per m² per24 hours at 25° C. at 1 atm. Sample product applications: Fruits such ascantaloupe, honey dew, tomatoes, apple, pears, cherries, grapes,peaches, nectarines, kiwi, strawberries, tomatoes, cucumbers (in generalcitrus, pome and drupe fruits, berries and greenhouse crops). Category3: Low Barrier (High Permeability) Film: Oxygen transmission rates of:25,000+over cm³ per m² per 24 hours at 25° C. at 1 atm Carbon dioxidetransmission rates of 25,000+cm³ per m² per 24 hours at 25° C. at 1 atm.Sample product applications: Mushrooms, asparagus.
 15. A system that canregulate relative humidity within the container within a range of 75 to94%, preferably between 75% and 85% for some foods by removing moisturefrom the food and the moisture generated from respiration. The resultingrelative humidity suppresses product decay due to micro-organisms.
 16. Asystem for the maintenance of fruit, vegetable and flower quality usingmodified atmospheres consisting of 1% to 50% carbon dioxide and 1% to15% oxygen.
 17. A system that independently controls modifiedatmospheres and relative humidity within the container at temperaturesof 0° C. to 25° C.
 18. A system where the sealed package of respiringproduce can contain a mass ratio (grams) to total package volume (cm³)of between 0.3 to 0.6. The headspace gas composition of the sealedpackage can be between 1% and 50% carbon dioxide and 1% to 15% oxygenwith an internal relative humidity of 75% RH to 100% RH.
 19. A systemwhich independently controls modified atmospheres and humidity withinthe container.
 20. A system where the three layer laminate oncecorrugated into a three or five layer construct may be die cut to a widerange of designs that may be further formed into a range of box designsthat provide for flexible vertical profiles that provide ventilationspaces between containers in a vertical stack and to provide air flowchannels within a stack, within an individual pallet and among palletsof containers constituting a trailer or storage room load.